Adherent cells have conventionally been grown on glass surfaces or on polymer substrates. The surfaces for cell culture are often pre-treated to enhance cell adhesion and proliferation. Matrices for adherent cells that allow on-demand cell detachment or cell release, have long been needed in biomedical and biological applications.
Cultured cells may be detached or released from cell culture supports by a variety of methods. Commonly used cell release methods comprise mechanical methods (such as scraping), treatment with proteolytic enzymes (such as trypsin), use of calcium chelators (such as EDTA), or a combination of such methods. However, many of these conventional cell release methods may cause adverse effects on cultured cells, and may modify their inherent structure and function. For example, treatment of cells with trypsin (i.e., trypsinization) is a harsh method, and is not desirable for delicate cells such as stem cells, due to its potential effect on cell phenotype. Moreover, trypsin is typically derived from animals, and may contain impurities like co-fractionated proteins or biological agents (such as viruses or mycoplasma). Impurities of animal origin may limit the use of released cells for critical applications such as cell therapy. Mechanical methods for releasing cells are labor intensive and are often impractical for industrial-scale cell culture applications.
Other non-enzymatic methods include physical methods that use ultrasounds or shock waves, which generate bubbles that facilitate cell detachment. Cultured cells from cell culture supports comprising thermoresponsive polymers like poly-N-isopropylacrylamide (PNIPAAm) may be released by cooling the cell culture support to a temperature in a range from about 4-20° C.
Efficient cell release is particularly important for high yield in industrial-scale cell culture processes. Therefore, there is an emerging need to develop better cell release techniques for fast, efficient cell detachment without affecting cell morphology and cell viability.